Ultrasound-promoted synthesis of novel N-arylamino-3,5′-biquinoline derivatives: their applications in live-cell imaging and in vitro anticancer activity evaluation

Abstract

A novel strategy for the construction of functionalized N-arylamino-3,5′-biquinoline has been developed. The reaction involves base-mediated Knoevenagel condensation between 2-chloro-3-formylquinoline and α,α-dicyanoolefines followed by a Michael addition and [1,5]-H shift, then the occurrence of intramolecular cyclization and an aromatization tandem reaction in the presence of Et₃N to make the target products. The reaction proceeds smoothly in EtOH at mild temperature to give the target compounds in modest to high yields (up to 92%) under ultrasonic irradiation. Single-crystal X-ray analysis was performed to confirm the structure of one of the typical products. In addition, the photophysical characteristics of the products were investigated through absorption and emission spectroscopy. This analysis reveals that the new heterocyclic system has impressive fluorescence characteristics. The anticancer activity in vitro was evaluated to determine anti-proliferative activity and toxicity against breast cancer for the target products. Moreover, the results show that the obtained IC₅₀ value for the 3c compound was lower than the others for MCF-7 cells than the untreated group that exhibited anti-proliferative activity and high toxicity against breast cancer cells. Furthermore, the 3c compound has high potential for use in cellular imaging with excellent photostability and chemical stability.